策略模式重構條件語句

經過策略模式來重構優化代碼裏面的switch/case分支代碼。極大程度上提升了程序的擴展性。固然，若是分支比較多，每次都須要新增長一個類，這的確是有點麻煩，能夠考慮使用反射來實現。
代碼：

namespace DP
{
    public enum State
    {
        Alaska,
        NewYork,
        Florida
    }

    public class CalculateShippingAmount 
    {
        public CalculateShippingAmount(IDictionary<State, IGetShippingAmount> dic) => _dic = dic;

        private IDictionary<State, IGetShippingAmount> _dic { get; set; }

        public decimal Calculate(State state) => _dic[state].GetAmount();
    }

    public interface IGetShippingAmount
    {
        decimal GetAmount();
    }

    #region 具體地址的實現
    // 具體
    public class GetAlaskaShippingAmount : IGetShippingAmount
    {
        public decimal GetAmount() => 15;
    }

    public class GetNewYorkShippingAmount : IGetShippingAmount
    {
        public decimal GetAmount() => 10;
    }

    public class GetFloridaShippingAmount : IGetShippingAmount
    {
        public decimal GetAmount() => 3;
    }
    #endregion

}

調用：

#region 策略模式重構 switch...case...
        static void SwitchToStrategy()
        {
            var dic = new Dictionary<State, IGetShippingAmount>
            {
                {State.Alaska,  new GetAlaskaShippingAmount() },
                {State.Florida, new GetFloridaShippingAmount() },
                {State.NewYork, new GetNewYorkShippingAmount() }
            };

            var calculate = new CalculateShippingAmount(dic);
            var result = calculate.Calculate(State.Florida);
            Console.WriteLine($"{State.Florida.ToString()}返回{result}");
        }
        #endregion

參考：使用策略模式重構switch case 代碼